Preparation of certain diarylacetonitriles



Patented June 15, 1948 BREPARATIONDF CERTAIN DIARYLAQETONI'IB LE August H: Homeyer, WebstenGrdires, and danet v S. Splitter, St. :Louis, Mo'., v -assig nors to Mal-t linckrodt Chemical Works, St; Louis, ;Mo., a cor .poration .of Missouri No'Drawing; Application December 9, 1 946;"

Serial No. 715,134:

aoiaims, (o1. ze -4cm I v This invention relatesto the preparation of: nitriles and more particularly to the preparation ordiarom'atic acetonitriles.

A ong 1 the objects of thisvinvention are the provisionof-animproved method for the preparationof diaromatic ace.tonitriles; the provision ofa method of the typeindicated which may .be easilyacarriedout with available materials; the provision of amethod ofthe type referred to which affords high yields of the desired nitrile, and the-provision of-a method of-the type indicatedwhich' may be utilized to prepare nitriles at relatively low cost. Other objects will bein; part-apparentand in part pointed out hereinafter. p

The invention accordingly comprises the steps andsequence .of steps, and features of synthesis, analysis, or metathesis, which will be exemplified in the processes hereinafter described, and the scope of the application of which will be indicated in the following claims.

According to the present invention it has been found that, according to theequation nitriles such as diphenylacetonitrile may be conveniently prepared by the reaction of a mandelonitrile and an aromatic hydrocarbon under the influence of anhydrous aluminum chloride. As an illustration, the preparation of diphenylacetonitrile is shown in the following equation:

The reaction takes place without difiiculty at convenient operating temperatures to form a high yield of diphenylacetonitrile.

The present invention is applicable not only to the preparation of diphenylacetonitrile but to the preparation of homologues thereof by the use of homologues of the reaction materials referred to above. For example, when toluene is substituted for benzene, the corresponding phenyltolylacetonitrile is obtained. Similarly, homologues of mandelonitrile may be substituted for mandelonitrile itself in the reaction referred to, to form nitrile products which are homologues of diphenylacetonitrile.

The following examples illustrated the/inven tion:

.Exsnrm 1 Diphenylacetonitrile Insa ..12 ntet 'rounnecked,nasaeqmp ed w h a, condenser stirrer, thermometer, and addition funnel, were placed anhydrous benzenev (4.5 liters).' and technical-anhydrous aluminum chloride (7 pounds). Operations were-conducted. in

a w l V n a dhood -Since hydrogen chloride and hydrogen cyanide were evolved.w The.. flask and =.con tents were cooledby means of anice bath. Mandelonitrile (1330 g.),was.added gradu, ally during a period of 3 hours .to the stirred reaction -mixture which was maintained ata temperature Not, ill-2.0" C. Afterathe. addition of the mandelonitrile. the reaction. mixture w heatedislowly to .a. temperature v.of .75? C. and maintainedat. this temperature for one hour. After cooling the reaction. mixture, water. was added cautiously through .the -addition funnel.

Cooling .was continued to control the. exothermic reaQtion,lwhi1e .a total of. 3 liters of .water was. added, Then excess benzene was removed by.

EXAMPLE 2 Phenyltolylacetonitrile A three-liter, four-necked flask, equipped with a condenser, stirrer, thermometer, and addition funnel, was set up in a well ventilated hood. Anhydrous toluene (1 liter) and a ydrous aluminum chloride (1%, pounds) were placed in the flask which was cooled by means of an ice bath. Mandelonitrile (266 g.) was added gradually during a period of 4 hours to the stirred reaction mixture which was maintained at a temperature of 10-20 C. After the addition of the mandelonitrile, the reaction mixture was allowed to stand at room temperature for 18 hours. Water (600 ml.) was then added cautiously through the addition funnel while the flask and contents were cooled by means of an ice bath. Then the excess toluene was removed by steam distillation. The

3 crude product solidified on cooling and was filtered from the aqueous part and washed with water. The crude product (250 g.-60% yield) was dissolved in hot methanol (400 ml.) and decolorized-with activated carbon. The alcoholic" solution was chilled and the product which crys-' tallized was filtered and dried. A second recrystallization from methanol yielded 203 g (49% 7.

yield) of phenyl-p-tolylacetonitri1e, melting point i 4 The solvent was removed from the combined mother liquors and the oily .residue then distilled under reduced pressure, yielding 116 g. (28% yield) of isomeric phenyltolylacetonitriles, B.-YP.' 1

As indicated above, analogous compounds con- 1 taining an alkyl substituent attached to the ring may be substituted for mandelonitrile and for benzene and toluene in the foregoing examples.-

aromatic compounds, taking part in character istic chemical reactions.

The benzene or toluene that is employed in the foregoing examples serves not'only as a reactant but part of it also serves as areaction me- 'dium.

be correspondingly reduced.- In such instances, equimolar" proportions of the aromatic compounds, such as benzene or toluene, and the mandelonitrile are preferred in order to obtain influence of anhydrous I If desired, however, a non-reactive sol-' vent maybe used for the latter purpose and the proportion of benzene or toluene employed may substantially complete utilization of the actants.

It is preferred that the initial stages be carried out at relatively low temperatures in order to keep the reaction under control eIn order to expedite: the reaction, itmay be completed at elevated temperatures, as for example, under re- .fiux, although in some instances this is not advantageous. 5 ,p The diphenylacetoni'trile or other nitrile products may be recovered from the reaction mixture byv the addition'of aqueous media otherthan wateri-f'desired. a f 1 In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in the above I processes without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting'sense.

We claim? it I 1. The method of making a compound selected I from the group consisting of diphenylacetonitrile i and alkyl substituteddiphenylacetonitriles which comprises mixing a compound-selected from the group consisting of mandelonitrile and alkyl substituted 'mandelo'nitriles with a compoundv se-' lected from a group consisting of 'benzene and alkyl benzenes; and aluminum chloride.

2. The method of making diph'enylacetronitrile which comprises mixing mandelonitriie, benzene,-

and aluminum chloride. V

3; The methodofmakingphenyltolylacetoni-' trile which comprises mixing mandelonitrlle with toluene and aluminum chloride.

AUGUST H. HOMEYER.

I JANET s. SPLITTER.

REFERENCES CITED 7 v The following references are of recordin the file of this patent:

Berkman et al., 953 (1940).

Catalysis (Reinhold) page) 

